Abstract

To support the industrial design and process development for the separation of xylenol isomers from coal tar, the present work was focused on 2,4/2,5-xylenol mixture as 2,4-xylenol and 2,5-xylenol have very close boiling points. Specifically, the kinetics of the alkylation of 2,4/2,5-xylenol mixture was investigated that formed the first step of the alkylation-distillation-dealkylation separation strategy. By quantifying the influence of various key factors on the reaction rate, the rate equations of 2,4-xylenol and 2,5-xylenol alkylation were determined as \({{r}_{{2,4}}} = 1538{{e}^{{{{ - 39{\kern 1pt} 360} \mathord{\left/ {\vphantom {{ - 39{\kern 1pt} 360} {RT}}} \right. \kern-0em} {RT}}}}}c_{{2,4}}^{{1.1}}P_{{{\text{PIB}}}}^{{1.0}}c_{{{\text{PTSA}}}}^{{0.4}}\) and \({{r}_{{2,5}}} = 516{{e}^{{{{ - 32{\kern 1pt} 241} \mathord{\left/ {\vphantom {{ - 32{\kern 1pt} 241} {RT}}} \right. \kern-0em} {RT}}}}}c_{{2,5}}^{{1.0}}P_{{{\text{PIB}}}}^{{0.8}}c_{{{\text{PTSA}}}}^{{0.7}}{\text{,}}\) respectively. The alkylation rate of 2,4-xylenol was notably higher than that of 2,5-xylenol. The influence of temperature, xylenol concentration and isobutylene partial pressure on the reaction rate of 2,4-xylenol was also greater than that of 2,5-xylenol, whilst the influence of catalyst dosage on the alkylation rate of 2,5-xylenol was found to be greater than that of 2,4-xylenol. The results can be potentially used for reactor design and process development for the separation of 2,4/2,5-xylenol mixture from coal tar.

中文翻译：

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二甲苯酚烷基化的化学动力学从煤焦油中分离它们的近沸点异构体

摘要

为了支持从煤焦油中分离二甲苯酚异构体的工业设计和工艺开发，目前的工作重点是2,4 / 2,5-二甲苯酚混合物，因为2,4-二甲苯酚和2,5-二甲苯酚的沸点非常接近点。具体地，研究了形成烷基化-蒸馏-脱烷基化分离策略的第一步的2,4 / 2,5-二甲苯酚混合物的烷基化动力学。通过量化各种关键因素对反应速率的影响，确定了2,4-二甲苯酚和2,5-二甲苯酚烷基化的速率方程为（（{{r} _ {{2,4}}} = 1538 { {e} ^ {{{{-39 {\ kern 1pt} 360} \ mathord {\ left / {\ vphantom {{-39 {\ kern 1pt} 360} {RT}}} \ right。\ kern-0em} {RT}}}}} c _ {{2,4}} ^ {{1.1}} P _ {{{\ text {PIB}}}} ^ {{1.0}} c _ {{{\ text {PTSA}}} } ^ {{0.4}} \）和\（{{r} _ {{2,5}}} = 516 {{e} ^ {{{{-32 {\ kern 1pt} 241} \ mathord {\ left / {\ vphantom {{-32 {\ kern 1pt} 241} {RT}}} \ right。\ kern-0em} {RT}}}}} c _ {{2,5}} ^ {{1.0}} P _ {{{\ text {PIB}}} } ^ {{0.8}} c _ {{{\ text {PTSA}}}} ^ {{0.7}} {\ text {，}} \）。2,4-二甲苯酚的烷基化速率明显高于2,5-二甲苯酚的烷基化速率。温度，二甲苯酚浓度和异丁烯分压对2,4-二甲苯酚反应速率的影响也大于2,5-二甲苯酚，而催化剂用量对2,5-二甲苯酚烷基化速率的影响最大。发现大于2,4-二甲苯酚。该结果可潜在地用于反应器设计和工艺开发，以从煤焦油中分离出2,4 / 2,5-二甲苯酚混合物。